Don’t make mountains out of molehills

Mounds of fresh topsoil and ridges from tunnels just under the sod mean one thing — moles. But before you succumb to the pest industry’s annual campaign against moles and rush to the local home- improvement center for traps and poison, consider what moles have to offer.

The presence of moles in the backyard becomes obvious in spring. As temperatures increase, they burrow closer to the surface in search of earthworms and other soil invertebrates. That’s why their surface tunnels become so apparent in March and April.

Any mole “damage” is cosmetic. Molehills and tunnels may be unsightly, but they hardly justify the expense of “pest control.” Mole tunnels aerate the soil and are easily eliminated by simply stepping on them. Mounds of fresh soil can be scooped up and placed in the garden. Instead of moles being a problem, they actually provide valuable ecological services.

Moles, though superficially rodent-like, are insectivores, kin to shrews. They have tiny eyes, lack external ear flaps and have a body well-suited to life underground.

Among the anatomical adaptations that permit moles a fossorial (burrowing) lifestyle are greatly enlarged front feet. The feet are broader than long and tipped with strong, well-developed claws. The upper arm bones are short and flat and attached to powerful digging muscles. The pelvic girdle and hind limbs are smaller, so moles can easily turn around in a narrow tunnel. And their teeth are needle sharp for capturing subterranean invertebrates.

Their permanent tunnels are 12 to 18 inches below the surface and are virtually undetectable. But their surface tunnels are evident, especially after spring and fall rains. Water loosens the soil and facilitates digging. And even though moles are one of nature’s most efficient diggers, they prefer loose soil to hardpan. In fact, soil type limits mole distribution. It must be loose enough to tunnel through, yet stiff enough to support the structure of the tunnel. Pure sand is too loose, and heavy clays are too dense.

Where moles occur, they are beneficial. Their tunnels till and aerate the soil and direct moisture to deeper soil layers. Though earthworms are their primary food, they also eat grubs, cutworms, slugs, snails, sowbugs and other lawn pests.

Moles rarely eat plant matter, though their presence can seem to harm bulbs and other plants. That’s because their tunnels may allow too much air into the soil and roots dry out.

Thanks to a variety of adaptations that make moles amazing digging machines, they can dig surface tunnels at a rate of 1 foot per minute. Deeper tunnels proceed at 12 to 15 feet per hour. Given these amazing digging rates, people often fear their yards are infested with dozens of moles. In fact, moles lead solitary lives and inhabit an acre or more, so a single mole can be responsible for all the tunnels and molehills in an entire backyard.

When digging, moles brace their hind legs against the tunnel wall and dig with their powerful forelegs. They push loose dirt under their bodies and kick it backward. When too much loose soil accumulates, they push it up vertical shafts to the surface to form the familiar molehills.

Molehills resemble miniature volcanoes but lack the central hole characteristic of crayfish chimneys. Gardeners should appreciate this natural source of fresh topsoil.

Three species of moles occur in the east. Hairy-tailed and eastern moles are the most likely species to be found in backyards. Recognize eastern moles by their short, naked tail. Star-nosed moles prefer wet, marshy soils and are easily identified by the 22 fleshy appendages that surround the tip of the nose.

Moles mate in early March. After a pregnancy of 30 to 45 days, females give birth to litters of four or five young. They leave the nest about four weeks later.

Golf courses, where perfectly manicured fairways and greens are essential, may suffer legitimate mole damage. But homeowners can deal with molehills and tunnels with a shovel, a heavy boot and a more tolerant attitude.

XSend questions and comments to Dr. Scott Shalaway, R.D. 5, Cameron, W.Va. 26033 or by e-mail via my Web site, http://scottshalaway.googlepages.com